Conventionally, automatic transmissions for automatically switching a transmission gear in accordance with the speed of a vehicle (vehicle speed), the accelerator operation by the driver, and the like are used in vehicles such as automobiles. PTL 1 discloses a transmission control device of such an automatic transmission, for example.
The transmission control device detects a crest on the course of the vehicle, and determines whether the vehicle can arrive at the crest at a predetermined vehicle speed or greater without a downshift when the distance between from the vehicle and the crest is within a predetermined range. When determining that the vehicle can arrive at the crest at a predetermined vehicle speed or greater without a downshift, the transmission control device restricts a downshift.
With this configuration, frequent transmissions are limited and inconvenience of the driver is reduced while enhancing the fuel economy.